Nanodiamonds are what make optical processors possible in real-life applications, not just inside the lab. Scientists have been able to make optical transistors--which are flow regulators, or simple switches to turn light beams off and on just as electronic transistors control electron flow--out of special dye molecules for a while. But though these optical devices do work as advertised, they only operate at extremely low temperatures, and that limits their usefulness.
The team that is pioneering the use of nanodiamonds is from the Institute of Photonic Sciences in Barcelona. They explain in their new Nature paper that the "optical transistor--the photonic counterpart of the electronic transistor--is poised to become a central ingredient in the development of optical signal processing" because they are so much faster than traditional switches, but only if they can be used in normal computing circumstances, like at room temperature.
With room-temperature-operable nanodiamonds, light switches might finally be able to reach production electronics. Essentially the team built their transistor by focusing a powerful green laser onto a nano-scale diamond particle that contained a single nitrogen vacancy--a special type of atom-scale defect in the otherwise perfect carbon crystal pattern of the diamond.
In its "on" state the green light was transmitted through the diamond, just as electrons would flow through a transistor that's turned on. To switch the transistor "off" they also shone a near-infrared laser onto the crystal, and this changed the way the nitrogen vacancy interacted with the green "signal" light. The switch worked in a time of about 100 ns, which is faster than the typical microsecond timescales for electronic transistors.
Essentially by stacking together lots of these nanodiamonds with some clever light guides for lasers you could create logic gates, and then proper integrated circuits that run on light, not electricity. And if you doubt that this could be possible, then you should check out the image to the right: This awkward looking thing, an inch or so across, is the first electronic transistor ever made, back in 1947. Considering it took until 1958 for the first (Nobel Prize-winning) working integrated circuit to be made of semiconducting transistors, we may hope that optical computers could arrive a little sooner than a decade away.